core: Removed unused VdcQueryType.CanFenceVds

Removed the CanFenceVds constant from VdcQueryType, as the
CanFenceVdsQuery associated with it no longer exists.

Change-Id: I5a9d97e7adbebccdc70760d0e11667d81bf55ff6
Signed-off-by: Allon Mureinik <amureini@redhat.com>